pMDIs are well known in the art of inhalation devices. It is therefore not necessary to describe the construction and operation of a pMDI other than in bare essentials.
A pMDI comprises a canister unit and a housing. The housing is generally tubular and formed of a plastic material, for instance by molding. The canister unit comprises a canister having one open end, typically made from a metal such as aluminum. The open end of the canister is sealingly capped by a metering valve assembly. The valve assembly includes a hollow dispensing member, usually in the form of a valve stem, which projects from the open end of the canister. Actuation of the metering valve assembly results in a metered dose of the aerosol formulation being dispensed from the canister through the valve stem.
In use, the sealed canister contains a pressurized medicinal aerosol formulation. The formulation comprises the medicament and a fluid propellant, and optionally one or more excipients and/or adjuvants. The medicament is typically in solution or suspension in the formulation.
The housing comprises an internal passageway having an open end. A nozzle block is arranged to receive the valve stem from the canister unit, and to direct the dispensed metered dose to a mouth piece (or nasal piece). In use, a patient in need of a metered dose of the medicinal aerosol formulation concurrently inhales on the mouthpiece and actuates the canister unit. The inspiratory airflow produced by the patient entrains the metered dose of the medicinal aerosol formulation into the patient's respiratory tract.
Dispensing devices are commonly stored in a sealed protection pouch inside a cardboard box or the like. Depending on the type of dispensing device and requirements related thereto, the protection pouch may be arranged to keep the dispensing device, and/or protected from moisture, contamination, and/or dust. The protection pouch is commonly made from a thin flexible material such as plastic film, coated paper, metal foil, laminates thereof or the like, hereafter referred to as pouch material.
WO-A-2001/87392 A1 describes a sealed pouch that allegedly prevents moisture ingress but is said to be permeable to the propellant gas of the pMDI contained therein. This is said to prevent the protective pouch from bursting if its interior pressure increases due to leakage of the propellant from the container. To further enhance moisture protection, a desiccant may be provided inside the pouch.
It has been concluded that current protection pouch designs may be susceptible to punctures due to fatigue failure in the materials and due to impacts from sharp edges on the inhaler. Fatigue failure frequently occurs at crease points in the pouch, where the material is worn and work hardened during vibration. The foil material punctures in the lower portion of the pouch, generally close to the sides and at evident fold points in the foil. This failure is caused by the vertical movement of the pouch and contents within the product carton during handling, transport, etc, whereby the foil pouch e.g. flexes at natural folds.
WO 2006/003386 discloses a package for a dispenser in the form of an inhaler, comprising a support arranged to suspend the dispenser in order to avoid unintentional actuation. Several types of suspension arrangements are proposed, all arranged to allow a controlled suspended movement of the inhaler inside the package. However, there are no specific provisions for avoiding punctures of the sealed pouch.